Can a freight train really move a ton of freight 436 miles on a gallon of fuel? Yes.

Yes, and some do even better. The figure used in the rail industry's advertising is a national average.
This question is generated by an advertising campaign by the railroad industry, which is arguing that a good way to reduce greenhouse gas emissions is to move more freight by rail rather than by truck. An example of the industry's ads can be seen on the Web site www.freightrailworks.org.